This invention relates to the dispensing of beverages. It is particularly concerned with the dispensing of beverages that are mixed at the point of sale from a concentrate, e.g. a syrup, and a diluent, usually plain or carbonated water and, although not intended to be limited thereto, will be described more specifically below with reference to such beverages.
It is an object of the invention to provide a dispenser whereby tie desired ratios of concentrate and diluent can be more accurately and reliably metered at an economical cost than is currently possible with existing dispense means.
Accordingly the invention provides a beverage dispenser comprising a valve housing having an inlet and an outlet for a concentrate and an inlet and an outlet for a diluent, a reciprocatable piston in a central passageway between the inlets and outlets, the piston being movable reciprocably between a first position in which flow to both outlets is blocked and a second position in which both outlets are open to flow, a flow rate sensor for the concentrate and a flow rate sensor for the diluent, the sensors being connected to a controller whereby the diluent flow rate is adjusted by movement of the piston according to the concentrate flow rate to achieve a predetermined ratio of concentrate to diluent for the dispensed beverage.
Thus any changes in the concentrate flow rate cause the controller to apply appropriate corresponding changes to the diluent flow rate to maintain the required ratio for the desired beverage.
Conveniently both outlets may lead directly into a mixing/dispense nozzle whereby the desired beverage can be dispensed into, e.g. a glass.
The reciprocating piston may be attached at one end to a setting mechanism to move it to open and close the outlets as required. The setting mechanism is preferably a stepper motor, e.g. of the pulsed, magnetically driven type, but may, for example, be a lever mechanism, a proportional solenoid actuator or a diaphragm operated mechanism.
The flow rate sensors may be, for example, flow turbines and the sensors may measure flow rate directly or by calculation from another property.
The invention enables a med beverage to be dispensed from equipment requiring only one setting mechanism for both the concentrate and the diluent.
Preferably, the piston is arranged to start to open the outlet for the diluent marginally before it starts to open the outlet for the concentrate as it may be disadvantageous to have any concentrate flow without the diluent, which could lead to undesirable stratification of the beverage. The concentrate outlet ten preferably fully opens while the diluent outlet is still only partially open. Further opening of the diluent outlet, up to its fully open extent then takes place with a constant fully open concentrate outlet.
The outlet for the diluent preferably includes a valve of the type described and claimed in our international patent application publication no. WO99/29619. That international application describes and claims a valve comprising a substantially rigid housing containing a passageway between an inlet and an outlet of the valve, a closure member movable in the passageway from a first position in which the valve is fully closed to a second position in which the valve is fully open, the closure member engaging the wall of the passageway to seal the passageway, the wall of the passageway or the closure member defining at least one groove, the groove having a transverse cross-section that increases in area in the downstream or upstream direction, whereby movement of the closure member from the first position towards the second position opens a flow channel through the groove. The groove(s) may be, for example, of tapering V-shape and will, for convenience, hereafter be referred to as xe2x80x9cV-groovesxe2x80x9d and the valves of this general type as xe2x80x9cV-groove valvesxe2x80x9d, although it will be appreciated that the grooves may, if desired, have a different tapering cross-section, e.g. of circular, rectangular or other shape.
It will be appreciated that when such a V-groove valve is utilised, the reciprocation piston may conveniently act as the closure member for the valve passageway.
The progressive increase or decrease in area of the groove flow channels can produce excellent linear flow through these V-groove valves, i.e. for a given pressure the flow rate is more directly proportional to the valve position than for conventional valves. This enables better control of the flow rate over the entire operating range of the valve.
Moreover, we have found that the V-groove arrangement may lead to reduced carbon dioxide xe2x80x9cbreak outxe2x80x9d from carbonated water so that the carbonation level of the dispensed drink remains at a satisfactory level.
The outlet valve means for the concentrate may simply be a passageway blocked by a seal on the piston and opened when the piston moves a sufficient distance to take the seal beyond the passageway. In one preferred embodiment, the passageway comprises a slot having a triangular shape, whereby movement of the piston initially opens the narrow end of the slot to flow of concentrate and then further movement exposes an increasing area of slot.
The piston may carry one or more seals to prevent the concentrate in the central passageway from leaking into the diluent inside the housing. The seals may be annular ring seals or diaphragm seals, the latter being moved from a compressed condition to an extended condition as the piston is moved to open the valve.
Essentially, the concentrate is allowed to flow through its outlet without continuous control of its flow rate once its outlet has been opened to the desired amount, e.g. fully opened but with its flow rate monitored. The concentrate flow rate is fed to the control means which then adjusts the diluent flow rate by appropriate movement of the piston by the setting mechanism to achieve the desired ratio for the concentrate/diluent mixture. It will be appreciated, therefore, that after the initial opening, and until closure of the valve, the cross-sectional area of the concentrate outlet will normally remain constant while the corresponding area for the diluent through its outlet valve can be increased or decreased as required.
Dependent on the flow rate measuring or calculation means used for the concentrates it may be necessary to monitor also the concentrate temperature as the viscosity of a viscous concentrate can significantly affect flow rate measurements. Again the necessary adjustments for viscosity effects can be pre-programmed into the control means.
The concentrate inlet may be provided with adjustment means that can be pre-set to provide a nominal flow rate of e.g. one fluid ounce per second or 4 fluid ounces per second dependent on the type and size of beverage normally to be dispensed out at the particular point of sale where the housing is installed.
The controller is conveniently an electronic controller, e.g. a microprocessor, which is preprogrammed to provide, in response to the concentrate flow rate data, actuation of the diluent valve opening to the amount necessary to maintain the desired ratio of the mixed beverage.
The invention provides significant advantages over conventional means of controlling mixing of concentrates and diluents. Conventionally the concentrate and the diluent each has a mechanical flow regulator and the overall flow rate and the concentrate/diluent ratio are pre-set. Such arrangements are prone to xe2x80x9cdriftingxe2x80x9d with use of the equipment so that the ratio gradually changes. Moreover, they are susceptible to manual interference, i.e. attempts to re-set them other than by a qualified service engineer. They require regular call-outs of service engineers to adjust to the desired levels. The present invention, however, automatically monitors flow rates in such a manner that the desired ratio is maintained continuously and automatically, thereby reducing service calls and unauthorised tampering.